I. Technical Field
The disclosed embodiments relate generally to image sensing devices and, more particularly, to an image sensing device for capturing images having separate luminance and chrominance sensors.
II. Background Discussion
Certain image capture devices, such as digital cameras and video recorders, can take video or still photographs, or both, by digitally recording images using an electronic image sensor. The continuing decrease in manufacturing costs of electronic imaging devices, combined with increasing functionality and enhanced user interfaces, have led to increased and widespread usage. Digital cameras and/or video cameras are found not only as freestanding devices, but are also incorporated into other electronic devices. For example, such devices may be incorporated into computers, mobile phones, handheld computing devices, and the like. These devices may also be used as computing peripherals to permit image capture, video conferencing, video chatting and so on.
Most electronic imaging devices employ a photosensor made of a grid of light-sensitive pixels. These pixels may measure light intensity (or luminance), as well as particular colors of light impacting them. The electronic representation of the particular colors of light may be processed to derive the chrominance component of the image, or the luminance portion of the image, or both. Typically, the luminance portion of a color image may have a greater influence on the overall image resolution than the chrominance portion. This effect can be at least partially attributed to the structure of the human eye, which includes a higher density of rods for sensing luminance than cones for sensing color.
While an image sensing device that emphasizes luminance over chrominance generally does not perceptibly compromise the resolution of the produced image, color information can be lost if the luminance and chrominance sensors are connected to separate optical lens trains, and a “blind” region of the luminance sensor is offset from the “blind” region of the chrominance sensor. One example of such a blind region can occur due to a foreground object occluding a background object. Further, the same foreground object may create the blind region for both the chrominance and luminance sensors, or the chrominance blind region created by one object may not completely overlap the luminance blind region created by a second object. In such situations, color information may be lost for the “blind” regions of the chrominance sensor, thereby compromising the resolution of the composite color image.